The Hedonic and Eudaimonic Motives for Activities (HEMA) scale measures well-being as a series of orientations. We investigated the HEMA scale’s psychometric properties among two Japanese samples in longitudinal studies over periods of one month (N = 385) and two months (N = 224). Exploratory and confirmatory factor analyses identified three subscales of the HEMA scale: hedonic pleasure orientation, hedonic relaxation orientation, and eudaimonic orientation. On average, at a given point in time, the correlations between subscales were r = .58 for the hedonic pleasure and hedonic relaxation orientations; r = .56 for the hedonic pleasure and eudaimonic orientations; and r = .26 for the hedonic relaxation and eudaimonic orientations—while the internal consistencies were αs > .80 for all subscales. In both studies, the three HEMA subscales had test-retest correlations averaging rs = .51, which suggests that these orientations are temporally quite stable, yet they are also amenable to change. Longitudinal analyses showed correlations between the HEMA scale and external criteria: hedonic pleasure orientation was associated with life satisfaction, positive affect, personal growth, purpose in life, and sense of meaning; hedonic relaxation orientation was associated with life satisfaction, positive affect, calm affect, and personal growth; and eudaimonic orientation was associated with life satisfaction, positive affect, personal growth, purpose in life, and sense of meaning. Implications for future research on the HEMA scale are discussed.